From public housing to luxury houses on The Peak, flat inspector Tsim Chai-nam has seen it all. And he has found one thing many homeowners have in common: the urge to rip out furnishings provided by developers.

"Homebuyers in Hong Kong have this bad habit," Tsim said. "They obey their interior designers, who will ask them to change everything to 'fit their character'.

The most outrageous thing I saw was this owner pulling out a first-class, expensive marble floor in the lounge. It was so finely paved, smooth and tight. But the owner chose to downgrade it with ceramic tiles

"The most outrageous thing I saw was this owner pulling out a first-class, expensive marble floor in the lounge. It was so finely paved, smooth and tight. But the owner chose to downgrade it with ceramic tiles. I can never understand why he did that."

In another "painful" case, Tsim recalled, the owner replaced a solid teak floor with fibre.

"Again he did what the designer told him. Sometimes these designers ask you to dump things because they can charge you money for their new materials, but few realise this."

It is also commonplace for people to knock out bathtubs and replace them with small shower bases, simply because they think these "look cool". But the change, according to Tsim, can easily lead to water leaks.

With 25 years of experience in construction and interior decoration, Tsim has specialised as a self-employed "flat inspector" for the past decade, checking out defects in the workmanship of newly decorated flats.

When he gets an order, he spends about an hour clambering all over a flat to spot problems ranging from scratched glass to a leaky washbasin, a loose tile or an uneven floor.

It's all done using simple tools including a rod, a spirit-level, a measuring tape and a mirror. Defects are marked with a yellow sticky note.

His service ends with a report printed on the spot for his clients who can then chase the developers or decoration companies to fix the problems.

Being a flat inspector is not a licensed profession like being an architect or engineer. After graduating from a diploma programme in civil engineering at Polytechnic University in 1988, Tsim worked for developers, a consultancy company and a contractor, responsible for planning, supervising and inspecting interior decoration schemes.

His portfolio includes residential projects, supermarkets and shops in railway stations.

It was his own unpleasant experience with the poor workmanship of the Housing Society flat he bought that triggered his decision to start up a business. "I wrote pages of complaints detailing the problems, the window leaks, the broken water switch ... I thought, 'Why can't I make this a job?'."

Over the years, developers had generally improved the workmanship in new homes, he observed, but it was the buyers' tendency to tear down everything that discouraged them, and in turn undermined the quality of the tradespeople's work.

The constant replacement of interiors was not just environmentally unfriendly, it also disheartened workers, especially the wall painters, he said. "They take their job less seriously, as they think what they do will be destroyed anyway. So it is no surprise that you find faults here and there in a new flat."

Tsim now appears regularly on a television property news programme, checking flats on a no-fee basis for homebuyers. This has served as good publicity for him, with reporters and homeowners respectfully calling him "Tsim Sir" for his authority and expertise.

Tsim Sir is also well known for criticising developers for building flats with an unreasonable layout and scale. In the television programme, he even lay down in a bay window in the maid's bedroom to show it was as big as the tiny room itself.

Sometimes developers' employees, mindful of what he has to say on television, will be present at the flat when they know Tsim has come at an owner's invitation.

"In the past developers would not give a damn. They stopped me from giving out flyers in the lobby," he said. "But as I'm getting more media exposure, they have recognised my work and my clients are usually successful in getting them to fix flats quickly."

Tsim has also met people who try to use his report to take revenge on the developer.

In one case an owner was irritated because the developer would not hand over the flat earlier than scheduled. So when he got hold of it, he asked Tsim to find as many faults as possible.

The inspector found himself in an awkward position.

"There were not many faults," he said. "All I could do was mark the dirty spots."

But he has a limit to what he will do. "Once a client wanted me to cause trouble for the decoration workers," he said. "He wanted to skip the payment. That was when I walked out."

This article appeared in the South China Morning Post print edition as If you're looking for flat flaws … Tsim's your man